Device for forced evacuation of air from kitchens

ABSTRACT

A ventilating system for a building including a suction chamber communicating through ducts with a kitchen and another space, a speed controlled exhaust fan communicating with the suction chamber for evacuating air from the kitchen and the other space, and a damper in the kitchen rotatably disposed in a duct to control the air being evacuated from the kitchen. The ventilating system may be used in a building having a plurality of kitchens and other spaces by utilizing a common duct for the kitchens and a common duct for the other spaces.

United States Patent Persson [541 A DEVICE FOR FORCED EVACUATION OF AIR FROM KITCHENS [72] Inventor: Sixten Ismael Persson, Stockholm,

Sweden 7 [73] Assignee: Luftkonditionering AB, Trosa,

Sweden 221 Filed: Jan. 19, 1971' [21] Appl. No.: 107,701

[52] US. Cl. ..-.....98/115 K [51] Int. Cl. ..F23j 11/00 [58] Field of Search ..98/l15 K, 102, 107, 110, 32, 98/33, 37, 39, 42, 43

[56] References Cited UNITED STATES PATENTS 2,223,287 11/1940 Kingsland ..236/49 X 2,665,840 l/1954 Powell ..98/33 R X 3,084,715 4/1963 Scharres ..98/1 10 X 1451 Sept. 19, 1972 3,150,584 9/1964 Allander ..98/43X 3,402,654 9/1968 Berst ..98/33 R FOREIGN PATENTS OR APPLICATIONS 418,748 10/ 1934 Great Britain ..98/43 A Primary Examiner-Edward J. Michael Attorney-Nathaniel L. Leek [5 1 ABSTRACT A ventilating system for a building including a suction chamber communicating through ducts witha kitchen and another space, a speed controlled exhaust fan communicating with the suction chamber for evacuating air from the kitchen and the other space, and a damper in the kitchen rotatably disposed in a duct to control the air being evacuated from the kitchen. The ventilating system may be used in a building having a plurality of kitchens and other spaces by utilizing a commonduct for the kitchens and a common duct for the other spaces.

8 Claims, 4 Drawing Figures PATENTEDSEP 19 m2 SHEET 3 OF 3 FIGJ.

PIC-3.3

DEVICE FOR FORCED EVACUATION OF AIR FROM KITCHENS The present invention relates to ventilation apparatus for ventilating a space, for example aroom of a dwelling.

Central evacuation systems for mechanically exhausting air from rooms of houses have a substantial advantage over conventional systems in which the air is exhausted by self-draught ventilation.

The minimum extraction of 80 m /h determined for kitchens ventilated by ventilation apparatus, has proved insufficient for achieving satisfactory ventilation in connection with the preparation of meals in kitchens. The extraction rate should preferably be increased at least to the magnitude of 250-300 In /h for obtaining an acceptable result. A permanent extraction rate of this magnitude is not, however, realistic in normal dwellings in view of the high cost of fuel and of an incalculable supply of fresh air which may cause draughts. It is desirable, therefore, to increase the ex traction rate instantaneously when required, for example when meals are being prepared.

In dwellings which have ventilation apparatus in kitchens, the extractor fans are usually either mounted in an exhaust opening of the kitchen or assembled with so-called kitchen hood located above the range or oven. The latter arrangement gave the best results. Such installations with a fan in each kitchen, are usually suitable only for single family houses, because a ventilation system common to several dwellings often causes disturbances in normal operating conditions, since when separate kitchen fans are connected to a common main line, an overpressure is often caused in the main line by the operation of one or several fans, which over-pressure results in a return flow of extracted air to rooms having no fan or where the fan is not in operation.

These problems do not exist in single family houses where normally the extraction duct opens directly to atmosphere. There are, however, other problems. Air extracted from a kitchen is replaced by fresh air flowing into the dwelling through other ope'nings, open doors from air, other rooms for example bathrooms and toilets. Such bad air thus flows to the kitchen instead of through evacuating ducts.

Houses are still being built with air extraction systems, in which the fixed extraction rate is of the order of 80 m /h and no provision is made for a momentary increasing of this rate when required.

The invention consists in a ventilation system for ventilating a kitchen or kitchens in houses or buildings including one duct for the kitchen or all the kitchens, one duct for evacuation of air from other spaces, a suction chamber connecting said ducts, to which chamber is connected an exhaust fan for maintaining in the suction chamber a constant vacuum at varying suction through the kitchen duct, the fan speed being controlled, and in which a housing arranged in every kitchen and connected to the duct via an evacuation channel is provided with a damper which has a central opening for continuous constant evacuation, and means for a further opening of the duct for momentary increased evacuation beyond the continuous evacuation.

The ventilation system according to the invention thereby renders it possible in apartment-houses to effect the rise in standard implied in an instantaneous forcing of the air exhaust and it also improves the conditions in one-family houses. I

The invention now will be described in more detail by way of example with reference to the accompanying v drawings in which:

FIG. 3 seen from above.

lnlorder to illustrate the general function of the invention and to show the problems which appear and are solved, reference is made to FIG. 1 wherein A and B are spaces connected to an evacuating system through ducts C, D and E and an evacuating fan F. To the fan F is connected a by-pass duct G in which a variable damper H is arranged. In the evacuating point of the space B a damper means J is inserted. This damper means has an adjustable blade which in one position engages the periphery of the duct and in a second position opens the duct. The damper blade has a central opening through which in the first-mentioned position of the blade permits a continuous, regular current of air. From the spaces A and B .a certain, fixed amount of air is sucked and will by the fan F be removed. Periodic removal of a greater than normal amount of air from the space B without disturbing the normal sucking from the space A will take place in the following manner.

Through the fan F is continuously passing a much greater amount of air than the air drawn from the spaces A and B. The greater part of the air sucked by the fan F will be returned through duct G to the duct E. The underpressure in the duct E will be controlled by damper H.

At a normal sucking of air from the space B the damper J is located in one of its end positions thereby tightening the blade around the periphery whereby all the sucking goes on through the central opening in the blade in the form of a well defined stream without turbulence or producing noise. To provide increased sucking of air from the space B, the blade will be replaced to its second position in order to open the duct. Because of the arrangement of the fan F the airstream flowing through the fan will be only slightly influenced by the increasing of the opening area at damper J, and thus the underpressure in duct E will not be influenced. The constant outsucking from space A is going on as before without any obvious change. The system has been described with one space A and one space B; however, the system is applicable at an arbitrary number of spaces A and/or B each group being connected to one or several ducts C or D.

The system according to the invention arranged in a multi-store house according to FIG. 2 will now be described.

A central suction fan 1 effects extraction of air from a plurality of kitchen hoods or housings 2 connected to a common conduit 3 disposed in close proximity above a cooking unit C with a suction surface S directed downwardly toward the cooking unit. The fan also effects extraction of air through ducts 4 from other spaces, such as toilets and bathrooms, the ducts 4 being connected to a common conduit 5. Other conduits similarto was; sites may be provided. Joining' 1 the conduits Brand S and thefan l. the re is' a suction chamberfi.

The fanl is pressure controlled suitable means sothatthere is a constant vacuum in the suction chamber; I .The ducts 3 ands are so dimensioned that evenat a hoods the friction pressure drop in these ducts. is negligible compared with the one-time resistances .in kitchen hoods and other evacuation points, The control of they vacuum maintainedin the suction chamber 6 by the fan-"canbe desigriedjin diit'ere'ntsvays. For example, pressure impulse vmemben T'may be arranged in the chamber .6 and-connected to aservomotor 8 for v'ary I I ing, via aspeed .control,. the rspeed'of-the fan. Alterna- The amount of air extractedfthrough a 1 kitchen shroud may be variable from 'rn'lh for basic extraction rate to 250- 300 mlh't'or'foi'ced' extraction rate. Preferably,:theapparatusissuch when forced extraction is effected mom or several kitchen hoods 2 functioning of'the remaining pasted the equipment i such. asthe basic extraction rate ofqair: through-other forced evacuation simultaneously in several kitchen tively, the servo-motor 8 maybe-arranged to operate a guide vanedamper in in parallelwith-the fan; I I I Each hood or housing ompr s a box member having 'a front-openingiin which a fatabsorbing'filter ,is

' mounted for-separating fat from theair removed from' the kitchen, and a verticallyextendingpipe or evacua-' tion channel -1 1 -(F.lG-.--3) part of which extends outside 'of'the box 9- for connection with a'conduit 18 of the ventilation system; Inside the pipe 11 there is'provided a damper operated by acontrol member on the front of the box membenf'l'othe connection opening of-the pipe 11 is:co'nnected a straightportion of the channel- 18.1" 1 The conduit 18 at the pipe 11 includes in its run thc lfan'inlet or areturn damper kitchen hoods Z'arid otherrducts 4 is not'appreciably-effectedthe vacuuminside theotherducts andshrouds remaining constant. It is also poseible to vary the, flow of air by an easily'adjl able device between ab'asicextraction-rate of 30 40.m'/h and a forced extraction rate of 250-30 ml i f he ad n ag m a as extraction rate of I @0 40 no produced. I v II Concerning the sound production at a forced extraction rate; 'in 'the kitchenhood it is an advantage Jif-a noticeable air sound is created so that there is audioindication, in addition to visual int'lication; that the issetfor-forced evacuation.

-. Whatlclaimz' l. A ventilation systemfor ventilating a-kitchen including a cooking ,unit and another spacein a building comprising first duct means for evacuation of air from the kitchen, second duct means for evacuation of air from the other space, a suction chamber connecting said first and second duct means,'an exhaust fan communicating with said suction chamber, housing means disposed-in. the kitchenabove-the cooking unit and communicating with said first. ductv meansv via an closest to the connection a straight portion inthe a direction ofthe air jetcoming fromthe opening 17, by which arrangement the air jet freely can be braked and thereby .therisk of secondary produced sound-be reduced. i 1 a f I Ofcourse, the dam r may be formed in any suitable manner. By way of examplesuch a damper is shown in EIGJandFlGld. I I II I I I The damper comprises a circular damper blade 14 pivotally mounted in'the'pipe 1 1 about'an axis 15 coinciden't'with adiameter of the blade Min-such a manner evacuation channel said housing means, having a suction surface directed downward toward the cooking unit and a filterjdisposed' between said suction surface andsaid evacuation channelya'nd damper, means disposed'in said evacuation channel having anopening there for normal continuous-constant evacuation and spaceisa bathroom.

that when the blade 14 is'in a plane at right angles'to a 1 plane containing the, central 'longitudinal axis of the pipe 11, the pipe is blocked and 'when the blade 14 is rotated through 90 the pipe 11 is unblocked. Around the periphery of the blade 14 is an annular resilient seal 16 having a cavity and having an outer diameter slightly in excess ofthe diameter of the blade 14, so that upon rotation of the damper blade to a closed position in which the blade blocks the pipe 11 the seal is trapped rotatably disposed in said evacuation channel and hav between the circumference of the. blade 14 and the inner walls of the pipe 11 thus providing an effective. sealing around the entire circumference of the blade ing 17 having a circular flangeof graduallyreducing diameter and beingso designed that the edge on the mouth is a tangent to an imaginary central'cylinder with the axis directed perpendicular to the plane" of the blade 14. In a closed position of the blade 14 the entire air flow sucked through the conduit Q opening 17, which by its shape ensures that even at a relatively high pressure dropabove the opening the air passes through in a well defined flow with a minimum of turbulence and-without risk of disturbing noise.

Centrally in the blade 14 there is provided an open tral opening in said damper blade is a cylinder directed 1 ing said opening centrally disposed "therein and a ,pe'ripheral'edge engaging the circumference of said evacuation channel when said damper'blade isjdisposed in a plane transverse to the longitudinal axis of said evacuation channel, said damper blade being rotatable Y through 90 for providing said increased opening area.

5. A system as claimed in claim 4 wherein said cenperpendicular to the plane of said damper blade having an open end extending in theevacuation direction.

6'. A system as clai'med'in claim 1 for use in a building having a plurality of kitchens and other spaces wherein a least one of said housing means, one of said evacuation said first duct means communicates with each'of the kitchens and said suction chamber, said second duct means communicates'with each-of the other spaces and said suction chamber, and each'of the kitchens has at channels and one of said damper means disposed in with reduced noise.

8. The ventilation system as claimed in claim 1 wherein said exhaust fan is operated at a speed to ex- ,haust more air from said suction chamber than is normally drawn from said first and second duct means. 

1. A ventilation system for ventilating a kitchen including a cooking unit and another space in a building comprising first duct means for evacuation of air from the kitchen, second duct means for evacuation of air from the other space, a suction chamber connecting said first and second duct means, an exhaust fan communicating with said suction chamber, housing means disposed in the kitchen above the cooking unit and communicating with said first duct means via an evacuation channel said housing means having a suction surface directed downward toward the cooking unit and a filter disposed between said suction surface and said evacuation channel, and damper means disposed in said evacuation channel having an opening there for normal continuous constant evacuation and being movable to provide an increased opening area for momentary increased evacuation greater than the normal continuous evacuation.
 2. A system as claimed in claim 1 in which the other space is a bathroom.
 3. A system as claimed in claim 1 and further comprising means for sensing pressure in said suction chamber, and a servo motor responsive to said pressure sensing means to control the speed of said exhaust fan.
 4. A system as claimed in claim 1 wherein said damper means includes a circular damper blade rotatably disposed in said evacuation channel and having said opening centrally disposed therein and a peripheral edge engaging the circumference of said evacuation channel when said damper blade is disposed in a plane transverse to the longitudinal axis of said evacuation channel, said damper blade being rotatable through 90* for providing said increased opening area.
 5. A system as claimed in claim 4 wherein said central opening in said damper blade is a cylinder directed perpendicular to the plane of said damper blade having an open end extending in the evacuation direction.
 6. A system as claimed in claim 1 for use in a building having a plurality of kitchens and other spaces wherein said first duct means communicates with each of the kitchens and said suction chamber, said second duct means communicates with each of the other spaces and said suction chamber, and each of the kitchens has at least one of said housing means, one of said evacuation channels and one of said damper means disposed in said evacuation channel, each of said evacuation channels communicating with said first duct means.
 7. The ventilation system as claimed in claim 1 wherein said evacuation channel has a straight portion extending upstream from said damper means whereby flow of air through said damper means is decelerated with reduced noise.
 8. The ventilation system as claimed in claim 1 wherein said exhaust fan is operated at a speed to exhaust more air from said suction chamber than is normally drawn from said first and second duct means. 